1. Field of the Invention
The present invention relates to ultrasonic diagnostic devices which possess an ultrasonic search unit of a radial scanning system.
2. Description of the Related Art
Endoscopes have been widely used for observations of organs within body cavities and a variety of therapeutic treatments using a treatment device inserted into a channel for passage as necessary.
With a type of endoscope having a channel for treatment device passage, ultrasonic diagnoses can be conducted by passing an ultrasonic probe into this channel, introducing it to an area to be diagnosed and then generating ultrasonic beams.
On the other hand, an ultrasonic probe having an ultrasonic search unit provided at the tip of an insertion part which is inserted into a body cavity and which enables ultrasonic tomograms to be obtained by the ultrasonic search unit has also been used. With the endoscope having a channel for treatment device passage in the insertion part, by protruding the treatment device through a delivery port at the tip of the channel, some treatments including collection of tissues with lesions and the like can be conducted.
There are several kinds of ultrasonic probes, including a radial scanning types to obtain ultrasonic tomograms in the lateral direction by scanning the probe in the direction which intersects at right angles with the insertion axis direction, a sector scanning type designed to obtain ultrasonic tomograms in the anterior direction by scanning the probe in, for example, the anterior direction which is parallel to the insertion axis direction, and other types.
For example, in U.S. Pat. No. 4,466,444 and Japanese Unexamined Patent Publication No. 7-289549, ultrasonic diagnostic devices which have structures where an ultrasonic search unit is provided at the tip part of an endoscope and upon rotation of this ultrasonic search unit, ultrasonic images of the section perpendicular to the insertion direction of the endoscope are obtained.
Moreover, Japanese Unexamined Patent Publication No. 62-176436 discloses an external type of ultrasonic search unit which obtains ultrasonic images of planes parallel to the insertion direction by directly rotating the ultrasonic search unit. In addition, Japanese Unexamined Patent Publication No. 62-231630 and Japanese Unexamined Patent Publication No. 1-136638 disclose ultrasonic search units having structures analogous to those of the above-mentioned Japanese Unexamined Patent Publication No. 62-176436.
Moreover, Japanese Unexamined Patent Publication No. 4-82540 discloses an ultrasonic probe in which two ultrasonic search units are provided at the tip of an insertion part and wherein these two ultrasonic search units are designed to scan in the direction vertical to the insertion direction and in the insertion axis direction, respectively.
Also, Japanese Unexamined Patent Publication No. 5-23337 discloses an endoscope in which an ultrasonic probe is inserted into a treatment device insertion hole such as a forceps channel or the like, and which has a protruding part with a tilted face located at the side of the opening direction of the forceps channel at the tip of the endoscope, a reflection plate provided on the tilted face, and a step part to fix the ultrasonic probe provided in the inside of the forceps channel, wherein the ultrasonic scanning direction can be changed and the diameter of the endoscope can be made small in size.
With the ultrasonic diagnostic device as set forth in the above-mentioned Japanese Unexamined Patent Publication No. 7-289549, however, ultrasonic images of a section vertical to the insertion direction of an endoscope can be obtained. Therefore, only one single cross section of a treatment device extended through a treatment device passage channel of the endoscope towards a diagnostic area is designated with almost punctiform lines on the ultrasonic images. Accordingly, it is inconvenient that the position of the tip of the treatment device can not be judged in the ultrasonic images.
As shown in FIG. 1, an ultrasonic search unit which is set forth in the above-mentioned Japanese Unexamined Patent Publication No. 1-136638 has a structure where an intermediate axis 104 is rotated by driving a motor 101 through spiral gears 102 and 103, and a pedestal 108 and a transducer 109 are rotated by rotation of the intermediate axis 104 through the first pulley 105, a belt 106, and the second pulley 107. In this device, the complicated structure makes the size of the tip part large.
Moreover, the ultrasonic probe of the above-mentioned Japanese Unexamined Patent Publication No. 4-82540 is disadvantageous in that the length of the hard body of the tip part becomes long due to the providing of two kinds of ultrasonic search units which differ in their scanning directions.
In addition, with the endoscope of Japanese Unexamined Patent Publication No. 5-23337, several problems have been encountered.
The first problem is that, although an ultrasonic probe is fixed by providing a step part, this fixing method may cause degeneration of ultrasonic images due to failure of steadily keeping a relative location between an ultrasonic search unit within the ultrasonic probe and a reflection plate provided in the endoscope.
The next problem is that, although the anterior scanning can be conducted by reflecting the ultrasonic waves emitted from the ultrasonic probe at the reflection plate provided in the endoscope to perform this scanning, it is required that an ultrasonic wave transmission medium be provided between the ultrasonic probe and the reflection plate. However, no structure is provided for this purpose.
Further, to insert the ultrasonic probe into a channel of the endoscope, and to conduct treatments under ultrasonic observation, two channels for treatment use must be provided in the endoscope. The problem is that, as a result, the overall diameter of the endoscope becomes large.